The patent document 1 describes an antivibration device including: a bottom plate horizontally and fixedly placed; a top plate placed above the bottom plate by a predetermined space and supporting an object such as a structural material to be supported; a middle plate horizontally placed between the bottom plate and the top plate and having a through hole at the center thereof; one first viscoelastic body connecting the bottom plate with the top plate through the through hole of the middle plate; at least three first compression coil springs placed around the viscoelastic body so as to extend m the vertical direction between the bottom plate and the middle plate; and at least three second compression coil springs placed at the same position as the first compression coil springs with respect to the horizontal direction so as to extend in the vertical direction between the middle plate and the top plate; wherein the first and the second compression coil springs which correspond to each other are placed around the central axle of the first viscoelastic body in a point symmetrical manner or in an equivalent angle intervals and a plurality of second viscoelastic bodies extending in the vertical direction so as to connect the bottom plate with the middle plate are placed at positions where the first compression coil springs are not interfered therewith with respect to the horizontal direction between the bottom plate and the middle plate.
The patent document 2 describes an active antivibration table including a bench having a planer shape for placing an equipment thereon; dampers supporting the bench at the four corners of the under surface thereon; a vibration sensor for measuring vibration of the bench; an actuator for moving the bench; and a controller for calculating a control output to the actuator based on vibration information output from the vibration sensor; wherein the active anti-vibration table is provided with a coil spring in the vertical direction used as the dampers and is provided with the actuator and the vibration sensor near the coil spring.